In conventional radio communication, in order to make bit reception errors due to fading less likely to occur, interleaving processing has been performed after an error correction encoding processing. In the interleaving processing, sequential coded symbols are assigned to different symbols on a time axis, or to sub-carriers which are as far away as possible from each other on a frequency axis.
For example, a WCDMA system is configured to perform interleaving processing on data to be transmitted in a TTI (Transmission Time Interval), for example, for 20 ms, 60 ms.
Meanwhile, in the OFDM (Orthogonal Frequency Division Multiplexing), data is transmitted on multiple sub-carriers. Thus, as shown in FIG. 1, the data is allowed to be interleaved in a frequency direction as well as in a time direction. Accordingly, a block of transmission data consisting of all OFDM symbols to be transmitted in each TTI (hereinafter referred to as a transmission time interval block) is used as a unit of interleaving.    Non-patent Document 1: 3GPP TS25.212 V7.3.0 (December, 2006)